class Reverse:
    "Iterator for looping over a sequence backwards"
    def __init__(self,data):
        self.data=data
        self.index=len(data)

    def __iter__(self):
        return self

    def next(self):
        if self.index==0:
            raise StopIteration
        self.index=self.index-1
        return self.data[self.index]
    
        
